How to Darken Brass With Baking Soda

Brass is an alloy containing copper and zinc. When copper objects are allowed to age in a moist environment such as humid air, eventually a patina will form. Patina is a coating of carbonate that forms on the surface of the object. The chemical reaction between the copper and the carbonate will change the color of the object to a green or a dark brown. Replicate the look of aged brass with a recipe for a brown patina.

Things You'll Need

Spray bottle

Hot water

Baking soda

Damp cloth

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Fill a spray bottle three-quarters full with hot water. Add in baking soda by the teaspoon, shaking the bottle to dissolve. Keep adding in baking soda until it stops combining with the water and merely floats on the surface.

Wipe the brass object with a damp cloth to remove any dirt or particles. Spray the object with the patina mixture. Apply an even coating and allow to dry for one hour in a humid place.

Spray on a second coat of the patina. Let sit overnight in a humid place for the patina to develop. Display or use object as desired.

Tips & Warnings

Humid air is required for the patina to develop its dark color. If the air isn't moist, invert a plastic bag over the brass object after the patina has been sprayed to encourage moisture.

Patina effects will wear off over time but you can repeat the process as much as you would like to make the color darker.